Treatment of heavy hydrocarbon oils with light hydrocarbons



J. M. WHITELEY ET AL ,110,845

March 8, 1938.

TREATMENT OF HEAVY HYDROCARBON OILS WITH LIGHT HYDROCARBONS OriginalFiled May 23, 1932 4 Shets-$heet l March 8, 1938. J. M. WHlT ELEY ET AL2,110,845

TREATMENT OF HEAVY HYDROCARBON OILS WITH LIGHT HYDROCARBONS OriginalFiled May 25, 1932 4 Sheets-Sheet 2 March 8, 1938. J. M. WHITELEY ET AL4 Sheets-Sheet 3 Original Filed May 25, 1952 x & Q 4 R h TREATMENT OFHEAVY HYDROGARBON OILS WITH LIGHT HYDROCARBONS March 8, 1938. J. M.WHITELEY ET AL v TREATMENT OF HEAVY HYDROCARBON OILS WITH LIGHTHYDROCARBONS Original Filed May 23, 1952 4 Sheets-Sheet 4 g 5w WK 5 k NRg H E Patented Mar. 8, 1938 PATENT OFFICE TREATMENT OF HEAVY HYDROCARBONOILS WITH LIGHT HYDBOCARBONS James M. Whiteley,

Roselle, and Gustav AlBeiswenger, Elizabeth, N. 1., assignors toStandard Oil Development Compan Delaware a corporation of Originalapplication my 23, 1932, Serial No. 612,-

908. Divided and 9 Claim.

This invention relates to hydrocarbon oils, especially petroleum oils,and more particularly relates to the treatment of these oils with lighthydrocarbons.

This application is a division of our copending application SerialNumber 612,908 filed on May 23, 1932.

The term light hydrocarbons will be understood to mean hydrocarbons ormixtures of hydrocarbons of 1 to carbon atoms in a liquid or liquefiedcondition.

We have found that light hydrocarbons have, at high temperatures, saywithin 50 to 100 F. of their critical temperature, a marked selectiveaction on hydrocarbon oils. We have also found that the selective actionof these light hydrocarbons may be varied by changing the temperature atwhich they are used.

In the present invention the light hydrocarbon solvent may compriseeither a .single light hydrocarbon or a mixture of light hydrocarbonsand instead of changing the composition of the solvent to vary itsselectivity, (in accordance with the method described by James M.Whiteley in United States Ser. No. 582,501 filed December 21, 1931) thetemperature at which it is used may be changed and the composition mayremain substantially constant.

The present invention therefore comprises the treatment of hydrocarbonoils with light hydrocarbon solvents either once at a constant hightemperature whereby the oil is separated into two components ofdissimilar characteristics, or repeatedly at a progressively changinghigh temperature whereby each component may be separated further intoother components.

The method of carrying out these treatments with the light hydrocarbonswill be fully understood from the following description read withreference to the accompanying drawings of which Figure 1 shows insectional elevation a type of apparatus suitable for carrying out asingle treatment at high temperature,

Figure 2 shows in sectional elevation a type of apparatus suited for acounter-current continuous treatment with a solvent of progressivelychanging temperature,

Figure 3 shows in sectional elevation a type of apparatus suited for anintermittent repeated extraction of the oil with a solvent ofprogressively changing temperature, and

Figure 4 shows in sectional elevation a type of apparatus suited for acounter-current treatment this application June 10, 1933, Serial No.675,240

and forces it through line 4 into mixer 5, and

pump 6 draws solvent from tank 2 and forces it through line 1 also intomixer 5, wherein oil and solvent are thoroughly cornmingled. From mixer5, the thoroughly mixed oil and solvent flow through line 8 into aheating means 9 wherein the mixture is raised to within 50 to 100 F. ofthe critical temperature of the light hydrocarbon solvent. Heat may beprovided by steam, by heat exchange, or by other means. From heatingmeans 9 the hot mixture flows through line I ll into a settling chamberll provided with insulating means 12 and fitted with steam coils l3whereby the required temperature can be maintained. The oil willseparate into '2 through line I9 by pump l9a.

The light oil freed from solvent is withdrawn from still 15 through line20 and may be passed to storage or to equipment for further treating.

The bottom layer in separating chamber II is withdrawn therefrom throughline, 2| and passed into still 22 fitted with steam coil 23. The solventvapors pass out of still 22 through line 24, pass through cooler 25 andthe condensed solvent is returned to solvent supply tank 2 through line19.

The heavy oil remaining in still 22 is withdrawn therefrom through line26 and passed to storage or to equipment for further treating.

Referring to Figure 2, numeral 30 designates a storage supply tank foroil to be treated. Pump the oil; but if the oil is introduced into themiddle of the tower the extraction will be carried out on both the lightand the heavy fractions of the oil, the former with a solvent ofprogressively decreasing density and the latter with a solvent ofprogressively increasing density all as will be more fully explainedbelow.

Tower 34 is an elongated vertical chamber which provides forcounter-current fiow of oil and solvent. It may be packed withcontacting means such as chain, jackstones, lumps of clay, or suitablydesigned plates, or may be without such contacting means. It may beprovided with an insulating coating 31, and with heating means such assteam coils 38 placed at intervals along its length by means of whichthe temperature in the tower may be progressively increased from bottomto top.

Numeral 38 designates a storage supply tank for the light hydrocarbonsolvent. Pump 48 draws solvent from tank 38 through line 4I and forcesit through line 42 into the base of tower 34 into which it may bedischarged through a suitable series of openings'indicated at 43.

In the tower the oil fiows downwardly in counter-current relation to theupwardly rising stream of solvent the temperature of which isprogressively increased as it rises by means of steam coils 88. The oilis thereby separated into a lighter soluble fraction and a. heavierinsoluble fraction. The former flows out of tower 34 through line 44 anddischarges into a still 45 wherein the solvent is separated from the oilby distillation. Vapors of solvent pass out of still 45 through line 48,flow through cooler 41 wherein they are condensed, and the recoveredsolvent is returned by line ,48, pump 48 and line 58 to solvent storagetank 38.

The heavier fraction of the oil passes out of tower 34 through line SIand discharges into still 52 wherein the solvent is removed bydistillation. Vapors of solvent pass out of still 52 through line 53,flow through cooler 54, and the condensed solvent returned to solventsupply tank 38 by lines 55 and 48, pump 48 and line 58.

Referring to Figure 3, numeral 88 designates a storage supply tank foroil to be treated. Pump 8| draws oil from tank 88 through line 82 andforces it through line 83 into a mixing device 84. Numeral 65 designatesa solvent supply tank. Pump 86 withdraws solvent from tank 65 throughline 81 and forces it through line 68 into mixing device 84 wherein oiland solvent are intimately commingled.

The mixture of oil and solvent then flows other hot gases. The heatedmixture discharges into a settling chamber II fitted with an insulatingcoating 12 and a heating coil I3 wherein the mass is allowed to stand.The oil separates into two layers, the top layer containing the lighterfractions and the bottom layer the heavier.

The bottom layer is withdrawn from settling chamber II through line I4.It passes to a second mixing device 15 wherein it may be commingled withadditional solvent supplied thereto 18 and discharges into a secondsettling chamber I8 provided like the first one with an insulatingcoating 88 and a heating coil 8|. After standing with the two layersseparate, the bottom layer is withdrawn through line 82 and subjectedagain to another extraction. This time with a solvent of still lowertemperature. Additional solvent is supplied through line 83 and the oiland solvent pass through mixing device 84, line 88, heating means 88 andline 81 into a third settling chamber 88, provided with insulatingcoating 88 and heating coil 88. A rd separation occurs and the bottomlayer m y be withdrawn and sub- Jected to as many further extractionswith solvent at progressively lower temperatures as desirable.

If settling chamber 88 is taken as the last chamber, the bottom layerwill be withdrawn therefrom through line 8| and discharged into a still82 wherein the solvent may be separated from the oil by distillation.Solvent vapors pass out of the still through line 83, flow throughcooler 84, and the condensed solvent returns to solvent supply tank 68through lines 95 and 88. The heavy oil remaining in the still iswithdrawn therefrom through line 81.

The top layers are withdrawn from the several settling chambers throughlines 88 and discharge into stills 88 wherein the solvent is separatedfrom the oil by distillation. Solvent vapors pass out of stills 89through lines I88, and flow through coolers IN. The condensed solventthen returns to solvent supply tank 85 through lines I82, I83, and 86.The light oil remaining in stills 89 is withdrawn therefrom throughlines I84. The several fractions of light oil so obtained may be blendedin any desired proportions, or may be maintained separate and worked upinto several different light oil fractions. It will be understood thatin place of using a separate still for the top layer from each settlingchamber, a single still into which the top layers from all the settlingchambers discharge may be used. Any other arrangement of stills may bemade.

Referring to Figure 4 which illustrates a type of apparatus for carryingout a counter-current treatment of both the lighter and heavierfractions in a series of stages, the apparatus is in general similar tothat shown in Figure 3 with these exceptions; the bottom layer formed inthe first settler instead of being forwarded to the second mixerand-settler is removed through line II8; the top layer formed in thefirst settler is withdrawnthrough line III and passed to the secondmixer and settler; the bottom layers from the second and third settlersare withdrawn through lines H2 and H3 respectively, and introduced intothe mixers ahead of the first and second settlers respectively. In otherwords, the bottom layers are continuously withdrawn and returned to thenext preceding stage instead of being forwarded to the next succeedingstage as in Figure 3, and the top layer in each settler is forwarded tothe next succeeding stage instead of being removed as in Figure 3.

' The top layer from the final settler is removed through line I andpassed into a still wherein the oil is separated from the solvent. Inthis method of operation the final top layer comprises an oil of greatlyimproved color over the original oil. It should be noted that in thismethod of operation the temperature is progressively increased fromstage to stage instead of progressively decreased as is the case intreating the bottom layer in successive stages as in Figure 3. In otherrespects the apparatus in Figure 4 may be substantially similar to thatin Figure 3, allowing for obvious modifications.

In the operation of our process the principal variable factors are thetype of material select d as the feed oil, the kindoi light hydrocarbonsolvent, the proportion of solvent to oil, the temperature at which thetreatment is carried out and the pressure maintained.

In general, our process is applicable to any type of heavy hydrocarbonmaterial, whether obtained from petroleum oil or its products ofdistillation or cracking, or from the products of the destructivedistillation or hydrogenation of petroleum oils, coals, tars, pitches,shales, lignites, bitumens and the like. Our process is also applicableto synthetic hydrocarbon oils, waxes or resins, prepared for example bycondensation or polymerization processes. It will be understood that atthe temperatures at which the extraction is carried out, most of thenormally solid hydrocarbons are above their melting points and thereforehave substantially the ,same solubility characteristics as oils. Ourprocess is particularly adapted, however, to the fractionation,purification and decolorization of petroleum oils, especially thelubricating fractions thereof.

The type of light hydrocarbons that may be used as the solvent in ourprocess comprise generally hydrocarbons of 1 to carbon atoms ormixturesof any 2 or more of such hydrocarbons. Thus methane, ethane, propane,butane, pentane, ethylene, propylene, butylene, amylene, and isomers ofthese may be used. The presence of small quantities oi'higher molecularweight hydrocarbons is not especially harmful but in general it isdesirable. to avoid the presence of these higher hydrocarbons. Ethane,propane and bu tane, or mixtures of ethane and propane or propane andbutane arev particularly satisfactory solvents for our purposes. Thegases obtained in the cracking of petroleum distillates and in thestabilization of gasolines are generally rich in the lighterhydrocarbons such as ethane, propane and butane and they furnish aconvenient and readily available source of the solvent hydrocarbons.

The proportion of solvent to oil may be varied within wide limits, butbetween 3 and 15 volumes of solvent per volume of oil is satisfactoryfor most purposes. Between 8 and 12 volumes of solvent per volume ofoil'is an especially suitable proportion.

The temperatures employed in the operation of the process in generalrange from the critical temperature to 10, 50, 100, 125 F. or more belowthe critical temperature of the particular light hydrocarbon selected asthe solvent. Thus for propane which has a critical temperature of about212 F., temperature may be decreased progressively from say 200 F. to175 to 150 to 100 to 75 F., and so on, the density and consequently theselectivity thereof increasing and decreasing respectively with thedecreasing temperature. For butane and pentane the temperatures ofoperation will be correspondingly higher and may be readily determinedfrom the critical temperature of each.

when using solvents comprising mixtures of two or more lighthydrocarbons, temperatures higher than those used with the lighter ofthe two or more hydrocarbons alone are generally required in order toobtainthe same selectivity. Thus when using a mixture of propane andhutane, the temperature necessary to obtain the same selectivity asexhibited by propane alone at a particular temperature must be near orabove the critical temperature of propane but below the criticaltemperature of butane. For example, a heavy bottoms oil obtained from aRanger crude is treated with 8 volumes of propane per volume of oil at atemperature of'about 158 F. and an 80% yield of an oil having a Sayboltviscosity at 210 F. of 114 secondsand a, color (Robinson) of 2% (dilute)is obtained. When a solvent comprising 8 parts of propane to 1 part ofbutane is used it is necessary to treat at a temperature of 180 F. inorder to obtain the same yield of the same quality oil.

Similarly when using a solvent comprising ethane and propane, highertemperatures are necessary than if ethane alone is used in order toobtain the same selectivity in each case.

The pressure in our process should in general be maintained suflicientiyhigh to retain the light hydrocarbons in liquid phase at the temperatureof working, but preferably not substantially greater than theequilibrium vapor pressure of the liquid at that temperature. Thispressure will be between say slightly above atmospheric and 50 or moreatmospheres depending upon the particular components of the solvent andthe temperature at which the treatment is carried out. If the solventcomprises a mixture of light hydrocarbons, the pressure necessary willbe close to the equilibrium vapor pressure of the lightest component ofthe solvent which is present in substantial amount.

The type of operation indicated in Figure 1, that is, a singleextraction with solvent at a high temperature is especially adapted forobtaining from a heavy oil a fraction of better quality with respect toviscosity temperature characteristics and gravity. It is also adaptedfor separating a heavy lubricating fraction into a lighter fraction anda heavier fraction, both of which fractions differ in characteristicsfrom the original oil.

The types of operation indicated by- Figures 2, 3, and 4, that is,counter-current or repeated intermittent extraction, are especiallyadapted for decolorizing and highly purifying heavy petroleum oilfractions and obtaining therefrom vainable lubricating 0115. By means ofthe successive treatment with solvent of progressively changing densityit is possible to extract from the oil solid impurities which could notbe removed in a single extraction. In the case of intermittentextraction it is possible to obtaina plurality of oil fractions ofdissimilar characteristics, and these may be blended in any proportionsto obtain blended oils of any desired characteristic. It is alsopossible by intermittent extraction to obtain in the last steps oils ofextremely high viscosities, say from 1000 to 5000 seconds Sayboltviscosity at 210 F. Oils of these high viscosities cannot ordinarily beobtained by the usual fractionating means due to the fact that theydecompose or break down at the temperatures necessary to vaporize themeven when distilled under high vacuum. Moreover, all of the severalfractions into which the heavy oil is separated by our process arecharacterized by much greater stability to heat and oxidation thanfractions obtained by distillation.

Prior to treatment according .to this process, the oils may be subjectedto preliminary purification treatments. Thus oils initially rich inasphaltic bodies may first be treated to remove a substantial portion ofthese materials. One

method of removing asphaltic bodies which is especially convenient inconnection with the present process is to treat the oil with liquefiedhydrocarbons such as propane or propane and ethane at normaltemperatures, say around 50 to 100 F. In this way the asphaltic bodiesare thrown out of the oil in a hard, granular substantially oil-freecondition and the remaining oil is already in solution in the lighthydrocarbon used in the high temperature treatment of the process hereindescribed. Other methods of removing asphalt may of course be used.

The oils may also be subjected to hydrogenation, phenol extraction,aluminum chloride digestion, acid and clay treatment and so forth eitherpreceding or following subjection to the light hydrocarbon solventtreatment. Dewaxing also may precede or follow the solvent treating.

and any suitable method of dewaxing may be used.

Following the purification of the material in accordance with the methodoutlined above, and before removing the solvent therefrom, a stillfurther purification may be conveniently and advantageously effected byfiltering the flux while still at the high treating-temperature througha bed of adsorptive material such as clay, charcoal and the like.Filtration of the oil or other hydrocarbon material while in hot lighthydrocarbon solutionproceeds at an extremely rapid rate andsubstantially larger yields of oil per ton of clay are obtained than canbe obtained by filtration in naphtha solution. The extent of theadditional purification moreover is substantial, and the oils filteredin this manner are comparable in purity. Y and color to oils obtainedonly after repeated subjection to other methods of purification.

It will be understood of course that the hydrocarbon material may befiltered through the solid adsorptive media while in hot lighthydrocarbon solution without a preliminary purification such asdescribed above. This would be particularly advantageous if the initialmaterial contains only a relatively small amount of colored or normallysolid bodies.

As an illustration of the type of operation shown in Figure 1, a heavydark-colored residuum obtained from a Ranger crude is first partial lypurified by treatment with propane at F. By this treatment a largeproportion of the asphaltic material is precipitated from the residuum.The partially purified oil then has the following characteristics:

Gravity, A. P. I degrees 22.5 Saybolt viscosity 210 F seconds 133.4Conradson carbon 2.48 Color, Robinson (dilute) 3/4 This oil is thendiluted with 8 volumes of propane and the mixture heated to 183 F.whereupon two layers form. After allowing the mixture to stand at thissame temperature the two layers are separated and the propane distilledoil from each. The two oil fractions so obtained have the followingcharacteristics:

The following table illustrates the eflect of varying the temperature onthe selectivity of the light hydrocarbon. The oil used is the sameRanger residuum as was used in the above example. The light hydrocarboncomprises propane and is used in the proportion of 8 volumes of propaneto 1 volume of oil. The pressures maintained at each temperature aresubstantially the saturated vapor pressures of propane at thosetemperatures:

This invention is not limited by any theories of its mechanism nor byany details or data which have been given merely for purposes ofillustration, but is limited only in and by the following claims inwhich we wish to claim all novelty inherent in the invention.

We claim:

1. The method of treating heavy hydrocarbon oils which comprises flowinga stream of such oil counter-current to and in intimate contact with astream of a light hydrocarbon solvent the temperature of which isprogressively increased in the direction of its flow from a temperaturesubstantially above the wax separation temperature to a temperature nearthe critical temperature of the solvent, removing a stream of oil andsolvent and recovering the oil therefrom.

2. Method according to claim 1 in which the initial temperature is from75 to 125 F. below the critical temperature of the light hydrocarbonsolvent and the final temperature is within 10 to 50 F. of the criticaltemperature of the solvent.

3.' Method according to claim 1 in which the light hydrocarbon solventcomprises a hydrocarbon of 3 carbon atoms.

4. Method according to claim 1 in which the light hydrocarbon solventcomprises hydrocarbons of 2 and 3 carbon atoms.

5. The method of purifying and decolorizing a lubricating oil fractionof petroleum which comprises causing a stream of the oil to flow incounter-current relation to and in intimate contact with a stream ofalight hydrocarbon solvent comprising propane, progressively increasingthe temperature of the solvent in the direction of its flow from a pointabout F. below to a point within a few degrees of the criticaltemperature of propane, removing a stream of oil and solvent, andrecovering the oil therefrom.

6. In the process of fractionating heavy mineral oils by means of lighthydrocarbons such as ethane, propane and butane at temperatures withinabout 50 F. of the critical temperature of the light hydrocarbon, themethod which comprises eifecting separation at temperatures successivelyincreasing from about 50 F. below the critical temperature of said lighthydrocarbon to temperatures near said critical temperature.

7. The method of treating a heavy hydrocarbon oil which comprisesdiluting the oil with several volumes of a liquefied normally gaseoushydrocarbon, heating the mixture to a temperature about 50 F. below thecritical temperature of the liquefied hydrocarbon at which the oil iscaused to separate into two liquid fractions, separating,

the two fractions, subjecting the lighter of the two fractions totreatment with additional liquefied hydrocarbons in a series of stagesat temperatures increasing to near the critical temperature of theliquefied hydrocarbon in the last stage, returning the heavier fractionfrom each stage to the next preceding stage, and removing the liquefiedhydrocarbon from the lighter fraction obtained in the last stage.

. 8. The method of treating a heavy asphalt containing hydrocarbon oilwhich comprises diluting the oil with several volumes of a liquefiednormally gaseous hydrocarbon, heating the mixture to a temperature about50 F. below the critical temperature of the liquefied hydrocarbon,removing the heavy asphalt-containing layer thereby caused toprecipitate, heating the remaining solution to a temperature about 10 F.higher than that at which the asphalt-containing layer was caused toseparate whereby the oil is separated into a soluble liquid fraction andan insoluble liquid fraction, subjecting the soluble fraction totreatment with additional liquefied hydrocarbon in a series ofsuccessive stages at increasing temperature, the temperature in the-laststage being close to the critical temperature of the liquefiedhydrocarbon, removing the insoluble fraction from each stage andreturning it to the next preceding stage, and recovering oil from thesoluble fraction obtained in the last stage.

9.' Process according to claim 8 in which pressure is maintainedthroughout the treatment sufficient to retain the liquefied hydrocarbonin liquid phase. I

JAMES M. WHI'I'ELEY. GUSTAV A. BEISWENGER.

